You could always take smaller steps towards all grain, that way you get to learn individual sub processes which you add one or two at a time for each brew.
So you've done several kit and kilo's. What about replacing the kilo of sugar with a kilo of malt extract in the next batch? I did this batch 3.
Adding just DME to a kit doesn't really get you much experience, bar melting the DME in your pot. It does give you a taste of beer without raw sugar added though which is definately an improvement. So, maybe try adding some flavour and/or aroma hops to the recipe. This gets you into boiling wort and hop additions.
Then try adding some speciality grains like crystal. Gets you into steeping grains, and boiling wort, and hop addtions. I found I started looking at the kit cans as a base with 60% of the fermentables. Adding speciality grains to a "generic" base like a Coopers Draught or similar can produce a variety of styles and much better tasting beer.
When you are ready you could try a full extract brew. No can. DME (or LME) + Grains + Hops. No can, no sugar. 100% your own recipe beer.
This is pretty much where I am right now. The reason I'm holding for a while and actually going back a step to can + grain + DME + hops is mostly cost and convience. Using the £9 kit can + £6 1Kg DME is cheaper than the £18 for 3kg of DME.
Logistics.... for all grain, the easiest entry points are, partial mash and BIAB. The former requires mashing eqiupment like a mashing tun and all that entails. The later, BIAB, is a full boil technique. Boiling 2 gallons on my cooker is hard as it is in a 12.5lt pot. Buying a bigger pot to boil 5 gallons (5.5gl really) is just not going to work on an electric counter hob unit.
So, yes I will hopefully try BIAB soon, but... it will be a 2 gallon batch.
So before you jump straight into all grain, be sure you know the requirements and have the equipment and make sure and consider the intermediate steps and the advantages in the beer produced, so you don't get yourself into so unnecessary diffs.
Paul